Toronto’s Buildings are Designed for the Sun

Here’s an interesting thought experiment: imagine Toronto without zoning regulations. In particular, imagine it without the “built-form envelopes”—essentially, invisible 3D forms that rise above every plot of land in the city—within which developers and architects must constrain their designs and ambitions.

It’s hard to know what wonders and monstrosities such a carte blanche would permit. But a section titled “Separation Distances” in the Tall Building Guidelines [PDF] offers a clue to just how jam-packed the city centre might otherwise be. This regulation stipulates that towers must be at least 25 metres apart, “so the downtown does not consist of a wall of tall buildings,” says James Parakh, the City’s urban design manager.

Rules like this give us a sense of just how eager private developers are to fill the air over our heads with new buildings. An unregulated urban landscape would engulf the street and all the little bipeds scurrying back and forth upon it, trapping us in deep ravines of concrete and glass. The resulting metropolis might not be as dense as the Borg cube, but it still wouldn’t be great. From that perspective, it’s somehow sweet and wonderful that the main force holding back this voracious claim on the sky is such a pleasant one. Namely, sunlight.

The need for natural light (and even the occasional cheek-warming blast direct from our nearest star) doesn’t generally require a lot of justification. For our collective wish to avoid a purgatory of darkness and to often have a good excuse to wear sunglasses, the City offers the phrase “pedestrian comfort,” which is a broad piece of lingo that also encompasses wind tunnel effects and accessibility. Clearly, pedestrian comfort is its own reward, and the rationale for sunshine needs no more nuance than that; instead, all the subtlety goes into implementation.

It works like this: the earth spins at a tilt relative to the sun, so as we make our annual orbit, we receive more or less sunshine—which translates to longer or shorter days—depending on which hemisphere we’re in. As far as City planners are concerned, the shorter days are a complete write-off. Nobody pays attention to sunshine in the winter, because if you’re not staying indoors, that’s your problem.

City planners start to care about sunlight and shade at exactly the same moment when everyone else does— as soon as the time we spend outside isn’t spent rushing to go back inside. Whenever a developer brings a design for a new building to the City for approval, they have to show how the extent of the building’s shadow on three specific days [PDF]: March 21, June 21, and September 21—the spring and fall equinoxes and the summer solstice. The former are the two days in the year when day and night are equal, and the latter is the longest day of the year.

Sadly, there’s no job where you get to stand on the street corner at astrologically significant moments and try to imagine the progress of theoretical shadows. What with the earth’s orbit being so consistent, somebody just wrote a computer program to figure it all out automatically. Developers plug in the coordinates and the proposed dimensions, and all the future shadows are thereby revealed, from sunrise to dusk on those three days. The resulting shadow studies [PDF] are rendered in colour-coded aerial maps that are hard to interpret—for the uninitiated, anyway.

Not all shadows are created equal. “They are all site-specific and context-driven,” says Parakh. In parts of the city reserved for tall buildings, a long shadow might not add much to the overall penumbra. But if a developer wants to throw shade on Nathan Phillip’s Square, for example, as was the case with the proposed 90-storey Sapphire Tower near Bay and Adelaide, City councillors might just put the kibosh to it.

Outside of the tall building zones on the city’s avenues, the primary purpose of shadow studies is to ensure that light reaches the opposite sidewalk when it’s traveling toward the earth at a 45-degree angle, which guarantees sunshine at noon. Practically, that means that the building can’t be taller than 80 per cent of the width of the right-of-way, a technical term that includes the street and both sidewalks. So the height limit varies, but usually it translates to about four or five storeys tall. Developers can build higher than that if they want to, but in order to continue to allow the light past, they have to step back each successive storey by three metres.

But it’s not like sunshine is an unmitigated good. Personally, I don’t like the way it makes my face scrunch up. For people like me, Parakh offers this reassurance: “Don’t forget that people always have a choice,” he says. “When it’s an east-west street and you don’t want sunlight, you can always walk on the opposite side of the street.” In most of Toronto, the sun is a decision you make at the crosswalk.